1. SIZE OF COCK RING
The size you choose depends very much on the size of your testicles. Take a cockring big enough so that you easily can get one of your testicles through. On the other hand – don’t use a cock ring to wide. It might be easier to put on but it might fall off when you are not erect. You should be able to wear a cockring not only during sex. This can give you an arousing feeling.
First, you pull through one of your testicles. Start with the one that is bigger. Then you pull the skin or push from the other side so that both testicles get through. Lubricating your balls with a silicon based lubricant helps a lot.
Once both of your balls are through the cock ring you can work on your penis. This will NOT work with an erection though. Push your cock down, make it flat and stick the foreskin (if you got) through the ring. Now try to reach the skin (or your head) from the other side and pull. Keep you cock flat on the other side with your other hand.
Once your balls and your penis is through the cock ring it should look like this. The balls in this graphic are very big but the principle is the same. Now you twist and turn the cock ring and pull the skin of your balls to get the ring as close to your body as possible. Using more lubricant is helpful